Farley`s Dodge Diplomat Forum

Forum Index => The Library => Topic started by: Reggie on December 28, 2007, 16:41:26

Title: Transmissions: 4-Speed or 5-Speed Manual Transmission Swap
Post by: Reggie on December 28, 2007, 16:41:26
Upgrading Your M body to Manual Transmissions

Below is edited and compiled information from member Thunderstruck (https://www.dippy.org/forum2/index.php?action=pm;sa=send;u=30) (Steve Knickerbocker) on swapping a 4-speed manual or 5-speed manual transmission into an M-body. Note that this swap requires considerable planning, knowledge of parts interchangeability, junkyard scrounging, mechanical and fabrication skills.  It is NOT for novices, nor is it for the faint of heart.  However, it is a very worthwhile and rewarding swap if you like going through the gears.

4-Speed (A833) Swap

Several issues with this. First, there were some 4 speed V8 M-bodies built by the factory but they are rare enough that I have never seen one. I have seen a ton of 4-speed F-bodies (Aspens/Volares) though, with 4-speed wagons being a common sight. There were many factory produced Slant 6 combos, so while you can use the pedal assembly out of any manual transmission Slant 6 M-body or F body, you cannot use the Slant 6 clutch linkage. Nor can you use the Slant 6 bellhousing, flywheel or clutch. 

If you wish to use factory parts, What you need is a V8 4-speed F-body  body donor, which IMO is the best donor candidate for this swap. So, what you need to swap an A833 4 speed into an M body is the following.

Do you have to do exactly what I did to swap in an A833? No, but using the factory stuff made it easy with minimal fabbing. You could probably use A body stuff, but I have no idea how close to working that stuff is.

5-Speed Swap

As for a 5 speed, there are many ways to do that. You can swap in a kit from several manufacturers based on the Tremec if you want:

(Note: the above kits are not specifically made for F/J/M cars, so you should check with the manufacturer.)

The 5-speeds used in Dakotas and Rams are real bulky. But in either case it's not nearly the issue in an M body, or any other transverse torsion bar car, as it is in older MoPars that use the transmission crossmember as the rear anchor for the torsion bars. The V6 5 speeds are fairly weak. They are Ok behind a stock 318, but I'd be leery behind a stock 360 or a warm 318. The V8 5-speeds from the trucks can be used, but they are truck transmissions, big and not geared towards (geared, lol) car use.

My preferred 5-speed setup, based on cost vs. performance is the R154 swap.

A real brief synopsis:

There is some custom fabbing needed to accomplish this. However, on a scale of 1 to 10 (1 being easiest) with the aforementioned A833 swap being a 1, I rate the R154 swap at a 3, the Tremec swap is a 6 (If you DIY and don't use a kit).

I might do this swap on my 65 Cuda and document it. Ought to be almost the same for an M body,
with a few minor exceptions, like the specific donor for pedals and any driveshaft length changes.

That about sums it up.

Good luck,

Links to Steve's site:

Additional 4-speed Swap Notes Compiled from Old Threads: